02-06-2012, 02:10 PM
CHILD SAFETY MANAGEMENT USING RF TECHNOLOGY
CHILD SAFETY MANAGEMENT USING RF TECHNOLOGY.doc (Size: 840.5 KB / Downloads: 118)
INTRODUCTION:
A lightweight transmitter is placed around a child's ankle or wrist. This allows the staff to monitor the child's whereabouts within the protected area. The transmitter sends a signal to receivers placed throughout the apartment complex. If the band is tampered with or if the infant or child is too close to a doorway, an alarm will sound. So the immediate and respective action can be taken by the parent.
Block Diagram Explanation:
In this project the child safety management has been achieved with RF Technology. There will be a RF band to the child with a transmitter connected with the band, which transmits the information of the child through the RF chip. The RF Receiver at the other end will receive the data continuously and store it in database. As such child is continuously monitored through the receiver, if the child crosses the prescribed limit which is bounded i.e. the receiver couldn’t track the information of the child then it will trigger an alarm to the person in charge, then they can take the required actions.
Circuit Diagram Explanation:
This is the FM transmitter circuit, which is tremendous range of about 1-2Km. The transmitter circuit described here has an extra RF power amplifier stage, after the oscillator stage, to raise the power output to 200-250 miliwatt. With a good matching 50-ohm ground plane antenna or multi-element Yagi antenna, this transmitter can provide reasonably good signal strength up to a distance of about 2 kilometers. The circuit built around transistor T1 (BF494) is a basic low-power variable-frequency VHF oscillator. A varicap diode circuit is included to change the frequency of the transmitter and to provide frequency modulation by audio signals. The output of the oscillator is about 50 milliwatts.
COMMUNICATION BETWEEN FM TRANSMITTER AND RECEIVER USING RF
In many situations a communication link between to devices becomes essential. This communication can be wired or wireless. If two devices are close to each other (like a MCU and a Memory) a wired link is preferred. How ever in many situations two devices are reasonably far apart. In that case a wireless link is preferred.
Two popular wireless communication technologies are:
Key features to implement:
• Interfacing using communication protocol like SPI /RS232 between the microcontroller and the RF chip.
• Writing the control algorithm to send data to the receiver which will in turn control the devices in the system.
• Developing the interfacing of the microcontroller to the sensing applications like temperature IC’s, relays.